Rep. Mike Michaud says he doesn't know who is behind the whisper campaign that had targeted him for being gay.

"I have no idea who is doing it," the congressman and candidate for Maine governor told Rachel Maddow on Tuesday. Michaud's spokesman had told local newspapers he's the victim of push polling in which his sexuality is asked about, though no one has claimed responsibility for the polls.

Maddow set up the interview by asking Michaud, a six-term congressman, why after so many years in elected office in Maine he only just came out. "Why now?" she asked. And Michaud blamed the whisper campaign against him.

"It never was an issue before," he said. "I've always ran for office talking about the issues. This is actually the first campaign where it's becoming an issue."

Michaud wrote a column published on Tuesday in two local newspapers and with the Associated Press in which he came out.

"Yes, I'm gay, but what's wrong with that?" he said on Tuesday in his first televised interview since writing the coming out column.

Michaud, a Democrat, faces incumbent governor Paul LePage in the 2014 gubernatorial race. Because of the Tea Party governor's reputation for strangely angry public statements, Rachel Maddow called him "the raging id of conservative American governors." He once chided a Democratic opponent with a graphic jab about anal sex, for example. Maddow kidded, "Kids, the governor is on TV again tonight. Viewer discretion is advised."

LePage opposes marriage equality, though it's now the law in his state.